All pumps on the aqua force range are equipped with a protection mechanism which the user the reduction in inlet diameter for solid of 6 mm x 10 mm depending on model to 2 mm wide makes it easier to so you can keep pond life such as kaulquappen water newts and small fish from falling into the chamber easy installation and maintenance the larger models 6000 8000 12000 and 15000 have a second inlet the use of an additional ski mmers or a satellite filter enables whats more the control a